The Muddy Charles is one of MIT's two pubs and the place of Ariely's experiment. Students that dropped by were offered two small free samples of beer, one labeled A and the other labeled B. Beer A was regular Budweiser whereas Beer B was a special mix called "MIT Brew", two drops of balsamic vinegar for each ounce of beer. After tasting the samples, participants were offered a free large glass of the beer of their choice.

Most of the participants that knew nothing about the vinegar before tasting the beers chose Beer B, the vinegary beer. But those that were offered more information before the tasting (Beer A was a commercial brew, Beer B had a few drops of balsamic vinegar in it) would wrinkle their nose at the vinegary brew and request Beer A instead. They believed beforehand that Beer B was going to be bad and after tasting it, they actually found it bad.

Now what happens if the presence of vinegar is revealed after tasting the samples instead of before? Can initial sensory perceptions be reshaped with new knowledge or is it too late to change the perceptions once they are established? Photo by jules:stonesoup.

It turned out that the participants to this new version of the experiment liked Beer B as much as those that knew nothing about the vinegar. Moreover, when asked whether they would like to make the "MIT Brew" themselves, they were willing to add the right amount of vinegar to their beer. Like the first group, they tasted the vinegary brew blind without any pre-conceived expectations and they actually liked the taste of it so they didn't mind giving it another try.

What happens is that our brain is always refining and distorting sensory information in order to construct a simpler picture of the world. If our brain has tried to represent everything as accurately as possible, we would be completely paralysed by information. Moreover, it cannot start from scratch at every new situation. Instead, it must build on what it has seen before so we can interact with our environment more decisively and make better sense of our complicated surroundings.

So next time you make a decision, be realistic—it's 100 percent biased.

Catherine Granger is a software engineer living in northern California. She created the Manage Your Cellar online wine inventory tool for collectors, edits the Purple Liquid blog, and notes that she very rarely writes about beer
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